Mass screening of newborn Swedish infants for alpha antitrypsin deficiency.

During the first year of mass screening for alpha1 antitrypsin deficiency, 108,000 newborn Swedish infants were examined. The screening method and criteria used for selecting infants with alpha1 antitrypsin deficiency were reliable. The Pi Z phenotype occurred at a rate of one per 1,433 infants, and the PiZ allele frequency was .026. The Pi- allele was found in one Pi Z and one Pi S infant. The Pi- allele frequency probably was below .001.     

The prevalence of alpha-1 antitrypsin deficiency in Ireland

Background

High frequency chest wall oscillation (HFCWO) is used for airway mucus clearance. The objective of this study was to evaluate the use of HFCWO early in the treatment of adults hospitalized for acute asthma or chronic obstructive pulmonary disease (COPD).

Methods

Randomized, multi-center, double-masked phase II clinical trial of active or sham treatment initiated within 24 hours of hospital admission for acute asthma or COPD at four academic medical centers. Patients received active or sham treatment for 15 minutes three times a day for four treatments. Medical management was standardized across groups. The primary outcomes were patient adherence to therapy after four treatments (minutes used/60 minutes prescribed) and satisfaction. Secondary outcomes included change in Borg dyspnea score (≥ 1 unit indicates a clinically significant change), spontaneously expectorated sputum volume, and forced expired volume in 1 second.

Results

Fifty-two participants were randomized to active (n = 25) or sham (n = 27) treatment. Patient adherence was similarly high in both groups (91% vs. 93%; p = 0.70). Patient satisfaction was also similarly high in both groups. After four treatments, a higher proportion of patients in the active treatment group had a clinically significant improvement in dyspnea (70.8% vs. 42.3%, p = 0.04). There were no significant differences in other secondary outcomes.

Conclusions

HFCWO is well tolerated in adults hospitalized for acute asthma or COPD and significantly improves dyspnea. The high levels of patient satisfaction in both treatment groups justify the need for sham controls when evaluating the use of HFCWO on patient-reported outcomes. Additional studies are needed to more fully evaluate the role of HFCWO in improving in-hospital and post-discharge outcomes in this population.

Trial Registration

ClinicalTrials.gov: NCT00181285     

Emphysema,cirrhosis, and heart block in a young patient with partial alpha 1 antitrypsin deficiency (PiMZ phenotype).

Severe lung disease and liver disease are not recognised features of the PiMZ phenotype, which is associated with alpha 1 antitrypsin deficiency. A 31 year old woman with this phenotype was found to have emphysema and complete heart block and showed evidence of hepatic cirrhosis, although her three sisters, all of whom had the same phenotype, were clinically normal. This case supports the possibility of a causal relation between the PiMZ phenotype and chronic lung and liver disease, but an association between alpha 1 antitrypsin deficiency and complete heart block could not be proved in this patient.     

Heritability of lung function in severe alpha-1 antitrypsin deficiency

Severe alpha-1 antitrypsin (AAT) deficiency is a proven genetic risk factor for COPD, but there is marked variation in the development of COPD among AAT deficient subjects. To investigate familial aggregation of lung function in subjects with AAT deficiency, we estimated heritability for forced expiratory volume in 1 s (FEV1) and FEV1/forced vital capacity (FVC) in 378 AAT deficient subjects from 167 families in the AAT Genetic Modifiers Study; all subjects were verified homozygous for the Z AAT deficiency allele. Heritability was evaluated for models that included and excluded an ascertainment correction, as well as for models that excluded, included and were stratified by a cigarette smoking covariate. In models without an ascertainment correction, and in all models without a covariate for smoking, no evidence for familial aggregation of lung function was observed. In models conditioned on the index proband with covariates for smoking, post-bronchodilator FEV1/FVC demonstrated significant heritability (0.26 +/- 0.14, p = 0.03). When we limited the analysis to subjects with a smoking history, post-bronchodilator FEV1 demonstrated significant heritability (0.47 +/- 0.21, p = 0.02). Severity rate phenotypes were also assessed as potential phenotypes for genetic modifier studies. Significant heritability was found with all age-of-onset threshold models that included smoking and ascertainment adjustments. Using the t-distribution, the heritability estimates ranged from 0.43 to 0.64, depending on the age-of-onset of FEV1 decline used for the severity rate calculation. Correction for ascertainment and consideration of gene-by-smoking interactions will be crucial for the identification of genes that may modify susceptibility for COPD in families with AAT deficiency.     

Binding of alpha 1 antitrypsin (alpha 1 protease inhibitor) to human lymphocytes

Radioiodinated α₁ antitrypsin has been found to bind to human lymphocytes. This binding is fast and reversible, and the cells can be saturated. Each lymphocyte can bind a maximum of approximately 1.2 × 10⁶ molecules of α₁ antitrypsin with an association constant of 0.7 × 10⁶ M^?1×l. The binding is inhibited by the addition of cold α₁ antitrypsin or Soybean trypsin inhibitor, and partially by α₂ macroglobulin. The data suggest that α₁ antitrypsin is likely to bind to a cell surface-associated protease. The addition of cell-free supernatants from lymphocytes incubated at 37°C was found to decrease the binding of α₁ antitrypsin, suggesting that the receptor is released from the cell surface.     

Association of cigarette smoking and CRP levels with DNA methylation in α-1 antitrypsin deficiency

Alpha-1 antitrypsin (AAT) deficiency and tobacco smoking are confirmed risk factors for Chronic Obstructive Pulmonary Disease. We hypothesized that variable DNA methylation would be associated with smoking and inflammation, as reflected by the level of C-Reactive Protein (CRP) in AAT-deficient subjects. Methylation levels of 1,411 autosomal CpG sites from the Illumina GoldenGate Methylation Cancer Panel I were analyzed in 316 subjects. Associations of five smoking behaviors and CRP levels with individual CpG sites and average methylation levels were assessed using non-parametric testing, linear regression and linear mixed effect models, with and without adjustment for age and gender. Univariate linear regression analysis revealed that methylation levels of 16 CpG sites significantly associated with ever-smoking status. A CpG site in the TGFBI gene was the only site associated with ever-smoking after adjustment for age and gender. No highly significant associations existed between age at smoking initiation, pack-years smoked, duration of smoking, and time since quitting smoking as predictors of individual CpG site methylation levels. However, ever-smoking and younger age at smoking initiation associated with lower methylation level averaged across all sites. DNA methylation at CpG sites in the RUNX3, JAK3 and KRT1 genes associated with CRP levels. The most significantly associated CpG sites with gender and age mapped to the CASP6 and FZD9 genes, respectively. In summary, this study identified multiple potential candidate CpG sites associated with ever-smoking and CRP level in AAT-deficient subjects. Phenotypic variability in Mendelian diseases may be due to epigenetic factors.     

A novel model and molecular therapy for Z alpha-1 antitrypsin deficiency

Animal models that closely resemble human disease can present a challenge. Particularly so in alpha-1 antitrypsin deficiency (α(1)ATD), as the mouse alpha-1 antitrypsin (α(1)AT) cluster encodes five highly related genes compared with the one in humans. The mouse PI2 homologue is closest to the α(1)AT human gene. We have changed the equivalent mouse site that results in the Z variant in man (Glu342Lys) and made both the "M" and "Z" mouse PI2 α(1)AT proteins. We have tested the ability of a small-molecular-weight compound CG to alleviate polymerisation of these mouse α(1)AT proteins as it has been shown to reduce aggregates of Z α(1)AT in man. We found that (1) CG specifically reduces the formation of polymers of recombinant mouse "Z" protein but not "M" protein; (2) whereas there is significantly more α(1)AT secreted from Chinese Hamster Ovary cells transfected with the mouse "M" α(1)AT gene than with the "Z" (20.8?±?3.9 and 6.7?±?3.6, respectively; P?相似文献   

Association of IREB2 and CHRNA3 polymorphisms with airflow obstruction in severe alpha-1 antitrypsin deficiency

Background

The development of COPD in subjects with alpha-1 antitrypsin (AAT) deficiency is likely to be influenced by modifier genes. Genome-wide association studies and integrative genomics approaches in COPD have demonstrated significant associations with SNPs in the chromosome 15q region that includes CHRNA3 (cholinergic nicotine receptor alpha3) and IREB2 (iron regulatory binding protein 2).We investigated whether SNPs in the chromosome 15q region would be modifiers for lung function and COPD in AAT deficiency.

Methods

The current analysis included 378 PIZZ subjects in the AAT Genetic Modifiers Study and a replication cohort of 458 subjects from the UK AAT Deficiency National Registry. Nine SNPs in LOC123688, CHRNA3 and IREB2 were selected for genotyping. FEV₁ percent of predicted and FEV₁/FVC ratio were analyzed as quantitative phenotypes. Family-based association analysis was performed in the AAT Genetic Modifiers Study. In the replication set, general linear models were used for quantitative phenotypes and logistic regression models were used for the presence/absence of emphysema or COPD.

Results

Three SNPs (rs2568494 in IREB2, rs8034191 in LOC123688, and rs1051730 in CHRNA3) were associated with pre-bronchodilator FEV₁ percent of predicted in the AAT Genetic Modifiers Study. Two SNPs (rs2568494 and rs1051730) were associated with the post-bronchodilator FEV₁ percent of predicted and pre-bronchodilator FEV₁/FVC ratio; SNP-by-gender interactions were observed. In the UK National Registry dataset, rs2568494 was significantly associated with emphysema in the male subgroup; significant SNP-by-smoking interactions were observed.

Conclusions

IREB2 and CHRNA3 are potential genetic modifiers of COPD phenotypes in individuals with severe AAT deficiency and may be sex-specific in their impact.     

Glucosidase and mannosidase inhibitors mediate increased secretion of mutant alpha1 antitrypsin Z

It is now well known that the addition and trimming of oligosaccharide side chains during post-translational modification play an important role in determining the fate of secretory, membrane, and lysosomal glycoproteins. Recent studies have suggested that trimming of oligosaccharide side chains also plays a role in the degradation of misfolded glycoproteins as a part of the quality control mechanism of the endoplasmic reticulum (ER). In this study, we examined the effect of several inhibitors of carbohydrate processing on the fate of the misfolded secretory protein alpha1 antitrypsin Z. Retention of this misfolded glycoprotein in the ER of liver cells in the classical form of alpha1 antitrypsin (alpha1-AT) deficiency is associated with severe liver injury and hepatocellular carcinoma and lack of its secretion is associated with destructive lung disease/emphysema. The results show marked alterations in the fate of alpha1 antitrypsin Z (alpha1-ATZ). Indeed, one glucosidase inhibitor, castanospermine (CST), and two mannosidase inhibitors, kifunensine (KIF) and deoxymannojirimycin (DMJ), mediate marked increases in secretion of alpha1-ATZ by distinct mechanisms. The effects of these inhibitors on secretion have interesting implications for our understanding of the quality control apparatus of the ER. These inhibitors may also constitute models for development of additional drugs for chemoprophylaxis of liver injury and emphysema in patients with alpha1-AT deficiency.